New Zealand Empirical Erosion Model (NZeem®)

Purpose

NZeem® is an empirical model that predicts mean annual sediment yield from a given catchment, based on annual rainfall, type of terrain and percentage of woody vegetation cover.

Description

NZeem® partitions the New Zealand landscape according to the factors controlling erosion: rock type, land form (especially slope angle), rainfall and land cover. The erosion co‑efficient (a) is a measure of inherent erosion susceptibility related to land-form characteristics (geology, slope angle, etc). The rock type and land-form data comes from the NZ Land Resource Inventory.

 The model is calibrated on about 200 sediment yield data sets from most regions in New Zealand. NZeem® is claimed to be applicable to all types and sizes of catchments (Dymond et al, 2010). It also builds on earlier work resulting in a database and digital map of mean specific sediment yield (kg / km2 / yr) produced by NIWA and Landcare Research as part of a project funded by the Foundation for Research Science and Technology for studying carbon transfers associated with erosion (Hicks et al, 2003).

Latest Version	1
State of Development	Released and updated

Scope

Outcome Areas	Environmental
Management Domains	Land, Natural Hazards
Intended End Users	Researchers, local and regional councils
Spatial Resolutions	10-100m
Spatial Extents	Local (i.e. Catchment or District), Regional, National
Spatial Dimensions	2D
Temporal Resolutions	Years
Temporal Extents	Decades
Steady State or Dynamic	Dynamic
Level of Integration	Environmental

Input & Output Data

Key Input Data	Land Use, Land Cover, Rainfall Geology and soil types
Input Data Formats	Raster GIS
Key Output Data	Erosion rate
Output Data Formats	Raster GIS

Accessibility

Open/Closed Source	Closed Source
Licence Type	Data licence required
Licence Cost (Non Commercial)	$0
Licence Cost (Commercial)	$0
Licence Purchase Contact	John Dymond DymondJ@landcareresearch.co.nz +64 6 353 4800 Landcare Research Private Bag 11052 Manawatu Mail Centre Palmerston North 4442, New Zealand

User Information

Operating Systems	MS Windows, Mac OS X, Linux, Dos executable
Software Needed	Internet Browser
User Interface	Please Select Web page
Ease of Use	Easy Just clicking in a web browser.
Use in Policy Process	Plan (Policy Formulation), Do (Policy Implementation)
Support	Contact John Dymond for any questions.
Users Forum	None

Technical Considerations

Programming Language	Two deployments: (1) Python+RIOS or (2) Imagine Spatial Modeller
Methods included for calibration and validation	Measurements of sediment yield in rivers to validate.
Methods included for managing uncertainty	Uncertainty has been assesed but is not part of the webpage
Analytical Techniques	GIS
Model Structure	This is in the manual
Keywords	erosion, sediment, rivers, farm plans, soil conservation
Linkages to other Models	Catchment Land Use for Environmental Sustainability (CLUES) Highly Erodible Land Model (HEL)
Links	Requires input from the Landcare Research's highly erodible land model. http://lris.scinfo.org.nz/layer/178-nzeem-erosion-rates-north-island/ http://lris.scinfo.org.nz/layer/176-nzeem-erosion-rates-south-island/
Key References	Dymond JR, Betts HD, Schierlitz CS (2010). An erosion model for evaluating land-use scenarios in New Zealand. Environmental Modelling and Software 25: 289-298 Dymond JR, Shepherd JD 2006. Highly erodible land in the Manawatu-Wanganui Region. Landcare Research Contract Report LC0607/027 to MAF Policy. Dymond J, Shepherd J and Page M 2008. Roll out of erosion models for Regional Councils. Landcare Research Contract Report LC0708/094 Barry, L. et al. 2011 Valuing Avoided Soil Erosion by Considering Private and Public Net Benefits. Paper at NZARES Conference

Associated Case Studies